1. Field of the Invention
This invention relates generally to processes for manufacturing cat litter products.
2. Background of the Invention
Materials traditionally used as cat litter due to their moisture absorbent characteristics include bentonite (montmorillonite) clays. Such bentonite clays include sodium bentonite, calcium bentonite, potassium bentonite, lithium bentonite, magnesium bentonite, or some combination of those clays. However, the moisture characteristics of those clays are not equal. Sodium bentonite is known to have better moisture absorbing properties than the other clays.
It is also known that sodium bentonite particles, upon absorbing moisture, swell and bind together as a mass (agglomerate). This is particularly desirable because the mass, including the liquid waste contained therein, can be easily and integrally removed and discarded. Thus, the source of odor in a litter box can be conveniently removed without the necessity of changing out the entire box. The result of this, however, is to place a premium on sodium bentonite for cat litter purposes. A need, therefore, exists for a process that combines clumping cat litter, such as sodium bentonite with other materials of lesser value, which can result in a final product which still provides for the clumping properties of the bentonite clay.
It is well known that waste cellulosic fiber and paper mill sludge, which are produced in large quantities in most industrial nations of the world today, due to the large usage of paper, constitute a substantial environmental problem. Paper mill sludge has substantially little usage as a material that can be employed in other industrial applications. Because of this non-utility, the paper mill sludge is merely discarded, along with other waste cellulosic fiber. This creates a tremendous disposal problem. A need, therefore, exists for an integral process from which a single source of paper mill sludge can be utilized in an economical continuous flow procedure to output usable product.
A particular known problem with all clay cat litter products and particularly clumping cat litter products is their weight/volume ratio. A significant amount of cat litter product is necessary to fill a litter box. It is known that such cat litter boxes are changed every 5-10 days, depending on the number of animals, to avoid odor problems. As a result, it is necessary to purchase a sufficient volume of cat litter in order to avoid frequent trips to the pet store or pet aisle of a grocery store. Moreover, as with most products, there are certain economics to be gained through the purchase of larger volumes. The problem is that the container for a sufficient volume and economy of clumping cat litter product is generally heavy, approximately 60 lbs./cubic foot or more for an all clay product. Such weights are awkward, and in some cases, impossible for some people to handle. A need, therefore, exists for an effective cat litter product with a reduced weight/volume ratio.
The present invention is an economical process that combines bentonite, or similar clays, that form a clump when in contact with cat urine, with cellulosic materials, preferably paper mill sludge and waste cellulosic fibrous material, to form a lighter weight scoopable cat litter. The process includes: (1) component introduction; (2) combining the component paper mill sludge including waste cellulosic fibrous material with bentonite clay (preferably sodium bentonite) in a mixing auger in varying percentages depending upon the desired end weight of the finished product; (3) transferring the mixture to a secondary rotating drum mixer for particle shaping; (4) drying the mixed and shaped particles; and (5) particle size separation (screening).
The finished product is a granule weighing between 20 lbs./cubic foot and 50 lbs./cubic foot. The granule is highly absorbent and forms a distinct clump that can be separated from the surrounding granules without falling apart. Unique characteristics of the process are the combination of heavy clay particles with light weight cellulose particles to form a new composite particle.
The process can be accomplished by using paper mill sludge or any such cellulosic material. As used herein the term xe2x80x9cpaper mill sludgexe2x80x9d encompasses bi-products of the production of paper as described above, mixtures of said bi-products and waste cellulosic fibrous materials, slurried waste cellulosic fibrous materials and slurried plant fibrous materials. Paper mill sludge for this process contains approximately 55-75% H2O by weight and clay that is 15% or less H2O. The H2O in the cellulose creates an environment conducive to blending the two materials in an agglomeration/swelling action that is characteristic of bentonite clay. When this agglomeration is dried, the particle decreases in size thus binding the two materials tightly to create a low dust, absorbent particle that has a lower weight/volume ratio than an all clay particle, that swells and forms a scoopable clump. Thus, the swelling/clumping properties of the bentonite clay are retained. The lighter weight/volume ratio is desirable for a variety of reasons: (1) less weight for the consumer to carry in the same volume; (2) less cost to ship from manufacture to retailer; and (3) a higher cost per pound for the manufacturer yet still providing the retailer the ability to sell the same volume for the same price as heavier scoopable cat litter products.
In an alternate embodiment of the process of the present invention, the paper mill sludge may be first dried and then run through a hammer mill in order to create a dry, small particle size cellulosic material. These small, dried particles are then dry blended with the bentonite clay. Moisture is then added to aggregate the cellulosic material and the bentonite clay. The resulting aggregate particles may then be shaped, dried and separated as in the process described above.
Odor control agents could also be added to the process during the component introduction step. Such odor control agents could include activated carbon, chabazite (zeolite) or any other known suitable material. When the particles are agglomerated according to the present process and then dried, the odor control agent is then trapped inside the particle. As a result, the odor control agent forms an integral part of the particle itself as opposed to added separately or sprayed onto the particles.
It is therefore an object of the present invention to provide an integral system for reclaiming paper mill sludge and waste cellulosic fibrous material into an environmentally acceptable product.
It is a further object of the present invention to utilize paper mill sludge and waste cellulosic fibrous material in the manufacture of a clumping cat litter.
It is still a further object of the present invention to combine bentonite clay with paper mill sludge and waste cellulosic fibrous material in the manufacture of a cat litter.
It is an additional object of the present invention to combine bentonite clay with paper mill sludge and waste cellulosic fibrous material in the manufacture of a clumping cat litter.
It is yet a further object of the present invention to combine bentonite clay with paper mill sludge and waste cellulosic fibrous material in the manufacture of a cat litter product with a lower weight/volume ratio that an all clay product.
It is still another object of the present invention to form a composite cat litter product containing an odor control agent(s) which are contained within the composite agglomerated particles.
A better understanding of the invention and its objects and advantages as well as further objects will become apparent to those skilled in this art from the following detailed description, taken in conjunction with the attached drawings, whether is shown and described only the preferred embodiment of the invention, simply by way of illustration of the best mode contemplated for carrying out the invention. As will be realized, the invention is capable of modifications and various obvious respects, all without departing from the scope of the invention. Accordingly, the description should be regarded as illustrative in nature and not as restrictive.